1. Field of the Invention
The invention relates to a flat panel display (FPD), and in particular to an organic electro-luminescent device improving quenching effect at the interface between the phosphorescent and the fluorescent materials.
2. Description of the Related Art
Organic electro-luminescent devices or organic light-emitting diodes (OLEDs) are active lighting devices using organic materials. Compared with conventional liquid crystal displays (LCDs), OLEDs are easily fabricated. Additionally, displays utilizing OLEDs require no backlight module, whereby the manufacturing process is simpler and costs are reduced. OLED technology is highly developed and can be employed in small panels such as those in personal digital assistants (PDAs) or digital cameras.
The organic electro-luminescent device typically comprises an anode, a cathode, and an organic electro-luminescent layer disposed therebetween. The organic electro-luminescent layer may comprise a hole transport layer (HTL) adjacent to the anode, an electron transport layer (ETL) adjacent to the cathode and a light emissive layer interposed therebetween. When an electrical potential difference is applied between the anode and the cathode, electrons are injected into the electron transport layer from the cathode and pass through the electron transport layer and the light emissive layer. At the same time, holes are injected into the hole transport layer from the anode and pass therethrough. The injected electrons and holes are recombined at the interface of the light emissive layer and the hole transport layer, releasing energy as light.
In a white organic electro-luminescent device, the organic electro-luminescent layer typically comprises a blue fluorescent material layer and green and red phosphorescent material layers. However, quenching may occur at the interface between the fluorescent material layer and the phosphorescent material layer, reducing the OLED brightness, making it difficult to improve device efficiency. Accordingly, there is a need to develop efficient OLEDs that are able to mitigate the quenching effect.